AIX System Performance Management Supplement: instructions on the use of Topas

The Topas command is used to monitor various system resources, such as CPU usage, CPU events and queues, memory and paging space usage, disk performance, network performance, and NFS statistics. It also reports on the consumption of system resources by processes assigned to different WLM classes. It also reports popular classes in the most popular processes and workload managers (WLM) in the system. Information about the WLM class is displayed only when WLM is active. The Topas command defines a hot process as a process that uses a large amount of CPU time. The Topas command does not have the option to log, and all information is real-time.

The TOPAS command uses the system performance measurement Interface (SPMI) API to obtain information. It is precisely because of the SPMI API that the system overhead is kept to a minimum. The Topas command accesses the Perfstat kernel extension using the Perfstat library call.

The TOPAS command provides real-time state monitoring of the system's processors. It displays a list of the most "sensitive" tasks for the CPU in the system. This command can be used by the CPU. The tasks are sorted by memory usage and execution time, and many of the commands can be set in interactive commands or in personal custom files.

The following is the syntax format for the command:

　　 topas [-d number-of-monitored-hot-disks][-h]
[-i monitoring-interval_in_seconds]
[-n number-of-monitored-hot-network-interfaces]
[-p number-of-monitored-hot-processes]
[-w number-of-monitored-hot-WLM classes]
[-c number-of-monitored-hot-CPUs]
[-P|-W]

-d Specifies the number of disks to be monitored. The default 2 disks are displayed in full if the screen shows enough space.

-I sets the time interval for monitoring in seconds. The default is 2 seconds.